Not applicable
The present invention relates to water heaters and boilers in general, and in particular to water heaters and boilers which incorporate sediment agitating apparatus.
Water heaters are widely used in both domestic and industrial settings. Hot water is used in many cleaning applications from dishwashers to clothes washer to showers. Hot water is also used to control the temperature of many industrial processes, and for space heating within homes and factories. Hot water is also has important recreational uses in pools, spas, and hot tubs. However, water as typically found in industrial and domestic settings is not a pure substance, and contains to varying degrees dissolved and suspended minerals. As a result, it is often recommended that water heaters be cleaned or flushed out periodically to remove sediments that tend to accumulate within the water heater tank, particularly on the bottom of the tank.
The sediments which accumulate within water heaters have many sources. Sand and silt often accompany water obtained from wells, and even where water is supplied through city mains. Particles of rust and other debris may be entrained in well water or water supplied from city mains. Various chemical processes may result in the precipitation of particles within the hot water tank. Certain forms of water hardness, including lime scale, may be precipitated when the water is heated. Change in temperature and/or the availability of oxygen can result of the precipitation of minerals such as iron. The typical hot water tank can be an ideal system for precipitating these various contaminants because of the long periods of quiescence where little or no mixing occurs within the tank.
The effects of minerals precipitating and accumulating on to the bottom of a hot water tank are highly undesirable, particularly if the water within the tank is heated by an oil or gas flame. The accumulation of sediments on the bottom of the tank reduces water heater efficiency by reducing heat transfer. More serious than the mere loss of water heater efficiency is the greater temperature gradient which results because the sediments insulate the water heater bottom from the water contained within the tank. Because of the insulating effect of sediments within the tank, a larger thermal gradient is necessary to transfer heat through the tank bottom and the insulating layer of sediments. Because the water within the tank is insulated from the tank bottom, combustion gases are able to raise the tank bottom material to a higher temperature than would otherwise be the case. This higher temperature results in greater thermal expansion of the tank bottom and greater thermal cycling. If the temperature of the tank bottom is raised to a sufficiently high temperature, the material properties of the steel used to form the tank bottom can be altered so as to reduce strength and durability. Increasing the temperature of the tank bottom leads to the breakdown of the protective glass lining of the water heater. Thus the insulating effect of sediments which build up on the bottom of the water tank produces increased thermal cycling and loss of material properties, break down in the glass protective coating, and sometimes in aerobic bacteria, which can contribute to tank corrosion. These factors can eventually lead to leaking of the water tank, which requires replacement of the water heater.
What is needed is a water heater with active means for preventing the buildup of sediments on the bottom of the water tank.
The water heater of this invention has a cold water inlet which is located near the bottom of the water heater tank. Cold water is injected through an inlet bushing which screws into a threaded boss in the side wall of the hot water tank. A female pipe thread on the inside of the cold water inlet bushing accepts a xc2xe inch male threaded pipe through which cold water is supplied to the water heater. A three-quarter inch diameter blind passageway is formed within the inlet bushing which extends radially inwardly from the tank outer wall. A outlet port with a diameter of xc2xd inch intersects the blind passageway at 90 degrees. The xc2xd inch diameter outlet port is positioned to discharge water within the tank along a line parallel to a tangent to the circular outer wall of the tank at the point the tank is penetrated by the inlet bushing. The inlet bushing accelerates the jet of water by creating a hydraulic pressure drop. The pressure is converted into velocity, and momentum transfer between the high velocity jet and the water contained in the tank results in the water within the tank rotating. The jet produces turbulent mixing between the injected water in the water contained within the tank.
The jet of cold water is only introduced into the tank when hot water is being drained from the hot water outlet, hence the turbulent mixing and circulation created by the inlet water jet places smaller particles of sediment into suspension which can be removed from the tank along with the hot water.
A drain is positioned next to and slightly below the inlet bushing so that when the water tank is drained, water from the inlet bushing circulates almost completely around the inside of the tank bottom before reaching the outlet, thus driving sediments toward the outlet for removal.
It is an object of the present invention to provide a hot water heater with longer service life.
It is another object of the present invention to provide a water heater that prevents the build up of sediments on the bottom of the tank.
It is a further object of the present invention to provide a water heater which provides for continuous flushing of sediments from within the tank.
It is also an object of the present invention to provide a water heater which better retains thermal efficiency over its operating life.